Bill Clinton suffered childhood abuse which may have caused him to philander and experience "bimbo eruptions" later in life, according to his wife Hillary.

In her most frank interview yet, the First Lady described her husband as "a hard dog to keep on the porch" but praised him for his leadership qualities.

Mrs Clinton, who is widely expected to run for the senate in the state of New York next year, said that her husband was a weak man who had achieved a remarkable amount considering his troubled childhood.

She said that she had hoped that he had got his philandering out of his system but she had been wrong before.

Talking in public for the first time about the Monica Lewinsky affair, Mrs Clinton said that the president was grieving at the time, following the death of his friend Vincent Foster, and he had denied his involvement to spare her suffering.

"He couldn't protect me, so he lied," Mrs Clinton said in an interview with the new magazine Talk. "This was a sign of weakness."

The woman who once mocked Tammy Wynette's Stand By Your Man attitude to marriage said: "Yes, he has weaknesses. Yes, he needs to be more disciplined, but it is remarkable given his background that he turned out to be the kind of person he is, capable of such leadership.

"He was so young, barely four when he was scarred by abuse," she added. "There was a terrible conflict between his mother and his grandmother." She said that a psychologist had told her that it was inevitable that a young child caught in the middle of such a battle would be damaged.

Mrs Clinton believes that this trauma affected his later life and may have led to the string of affairs which have done much to damage his credibility and his presidency.

Only last week, Linda Tripp, who secretly recorded Monica Lewinsky's telephone confidences about her relationship with Mr Clinton, was indicted by a grand jury in Maryland for illegal taping telephone calls. Ms Tripp's tapes were used to investigate the affair that led to impeachment proceedings.

Lawyers for Ms Tripp, who did not tell her then friend Monica Lewinsky that she was recording her most intimate conversations, claimed at the weekend that their client was a victim of a "shameful vendetta" being carried out for political motives.

Mrs Clinton likened her husband's infidelity to an addiction such as drinking or gambling and said that only he could actually end it.

"I thought he had conquered it," she added. "I thought he had understood it but he didn't go deep enough or work hard enough."

Asked how she faced the possibility of separation if she became a New York senator and her work took her aware from home, she said: "He's responsible for his behaviour whether I'm there or 100 miles away."

Mrs Clinton has always previously avoided talking about her husband's behaviour in interviews. She had become adept at politely diverting such inquiries.

Her cover story interview will be used by her supporters as a sign of her candour and tolerance and by her enemies to mock her. By giving such a frank interview in a magazine based in New York she has also given another very clear signal that she is intent on running for the Senate.

She is currently on a "listening tour" of New York state and at the weekend she met farmers, vineyard owners and academics from Cornell university in Ithaca.

Asked to comment on a report in the Wall Street Journal that she would be taking a job as head of the World Bank rather than running for office, she replied: "Gee, I didn't know it had been offered to me." She said she was more and more excited about the possibility of the senate race.

Last week, her likely Republican rival, the New York mayor, Rudolph Giuliani, visited Mrs Clinton's home territory of Little Rock, Arkansas, to raise funds and make some jokes at her expense.

Mr Giuliani pointed out that she had never lived a day in New York but Mrs Clinton's supporters countered by digging up an article written by Mr Giuliani when he was a Democrat and supporter of the late Robert Kennedy, in which he attacked those who accused candidates of being carpet-baggers.